The present invention relates to methods for evaluating the effectiveness of volatile insect control chemicals, such as insect repellents and insecticides. “Insect control” is defined as including the repelling, killing, rendering inactive, or otherwise affecting the behavior of insects or of other arthropods commonly controlled with insects. More particularly, the invention relates to the use of traps and other insect monitoring devices to test the effectiveness of various chemicals (sometimes referred to herein as “actives” or “active ingredients”), chemical delivery systems, and concentrations, while reducing the need to expose humans to the risk of being bitten during such efficacy experiments.
Various devices such as mosquito coils, heatable impregnated mats, heatable wick-type dispensers, burnable candles, and other dispensers of insect control actives disperse insect control actives into the air. Some require externally applied heat or applied blown air, while others do not. For purposes of the present application, all volatile delivery devices are being referred to, except as expressly stated, and will sometimes be referred to simply as the “products.”
In the course of developing such products, tests involving human test subjects have traditionally been used in order to guide efforts to optimize concentrations, heating conditions, air flow conditions, and other factors. For example, human test subjects have been positioned in a test area and exposed to the volatile insect control active ingredients delivered by a product and potentially also to biting insects such as mosquitoes or flies. The human test subjects have typically stayed in the test area for a set period while the degree of insect activity was observed, including insect lands on the human test subjects and even possible biting.
This process sometimes exposes human test subjects to higher levels of active than are later determined necessary for protection, it requires human test subjects to be willing to be exposed to insect activity and even biting, and it requires compliance with environmental and ethical protocols relating to human testing. Further, such testing requires obtaining enough human test subjects to establish statistical assurance. Moreover, insects respond differently to different individual human subjects, particularly when they have significantly different body temperatures, odors, and/or rates of emission of carbon dioxide introducing difficult to quantify variables from test to test.
A wide variety of insect traps are known, including some primarily intended for trapping mosquitoes and/or other flying insects. A well-known mosquito trap is the Center For Disease Control trap #912 which generates carbon dioxide as an attractant for mosquitoes. Center For Disease Control trap #512 is very similar to trap #912 and can be used in much the same way as the #912 trap. Although both of those traps are capable of generating carbon dioxide, it is also possible and may be operationally preferable to dispense carbon dioxide via the traps but drawn from a tank or other separate source. See generally FIG. 1.
In U.S. Pat. No. 7,275,499 there was discussion of using a cork impregnated with a repellent to partially test the effectiveness of the repellent by viewing how long mosquitoes stayed away from the corks that were so treated. However, this test system was not well suited to take into account a variety of other variables (e.g. adjustments to the dispensing product).
U.S. patent application publication 2007/0154504 proposed testing repellent effectiveness using a Petrie dish holding a repellent reservoir, and observing how long an insect stayed near the chemical. This only evaluated a limited range of characteristics, and in any event is an awkward technique with respect to flying insects as distinguished from cockroaches.
U.S. Pat. No. 6,585,991 disclosed that an array of baits and attractants could be positioned in an area for monitoring termite presence.
In B. Collier et al., Field Evaluation Of Mosquito Control Devices In Southern Louisiana, 22 J. Am. Mosquito Control Assoc. 444-450 (2006) there was a description of using a trap that generated carbon dioxide to test the effectiveness of various insect control devices in suppressing insect populations. However, the test systems described therein were not suitable for precisely measuring certain parameters of effectiveness, such as how soon the product becomes effective, how long it remains effective, and what it is effective against over varying time periods.
In unrelated work, there have been a variety of attempts, primarily by the United States Department Of Agriculture, to provide various devices to analyze the number and type of insects falling past a monitoring point (e.g. using infrared or other counting devices). These systems were primarily intended to monitor infestation in stored grains or the like. See e.g. U.S. Pat. Nos. 5,646,404, 6,707,384 and 6,882,279.
As such, there is still a need for improved methods for efficacy testing of insect control products which minimize the need for human subjects, yet evaluate a wide variety of device and use condition factors.